A good-looking hairstyle is now generally seen as being an essential part of a groomed appearance. Current fashion trends are dictating more and more hairstyles which are considered to be chic but which can only be achieved with many hair types by using firming substances, or they have to be maintained for a long period of time of up to several days. Thus, hair treatment agents, which provide the hair with a permanent or temporary shape, play an important role. While permanent shaping modifies the chemical structure of the keratinic fibers by reduction and oxidation, modifications of that type to the chemical structure do not take place with temporary reshaping. Appropriate agents for temporary shaping usually contain synthetic polymers and/or waxes as the firming substance.
The most important property of an agent for temporary shaping of keratinic fibers, herein also termed styling agents, is that the fibers when treated when in their newly remodelled form—i.e. the fibers have been styled—are provided with as strong a hold as possible. When the keratinic fibers are human hair, this is also known as a strong styling hold or a strong hold for the styling agent. The styling hold is essentially determined by the type and quantity of the firming substances used, but the other components of the styling agent and the form of application may also have an influence.
In the field of the temporary shaping of keratinic fibers, spray application of appropriate cosmetic preparations is of particular importance, wherein as a rule, the preparations are applied using pump sprays or aerosol sprays. In this regard, the cosmetic preparations are packaged in a dispensing device from which they are sprayed, either by employing mechanical force, or with the aid of a propellant through a valve. Both methods have obvious disadvantages. While pump sprays are not usually suitable for the prolonged, uniform application of cosmetic hair preparations, aerosol sprays are based on the use of propellants or propellant gases which on the one hand do not have any cosmetic action and on the other hand, can risk harming the consumer if handled ineptly.
In the light of this, there is a need for alternative methods for spraying cosmetic hair preparations. Flash evaporation has proved to be such an alternative spraying method. In this method which, for example, has been described in international patent application WO 2001/83071 A1 (Henkel), a fluid or pasty composition containing a solvent is heated in a sealed chamber to a temperature which is above the boiling point of the solvent, whereupon a positive pressure is produced in the composition. Upon release (reduction) of the pressure, the liquid evaporates and can then, for example, be sprayed using a suitable nozzle.
Although flash evaporation is thus in principle suitable for spray application of cosmetic hair preparations, at the same time, however, not all cosmetic hair preparations can be sprayed using a flash evaporation method. This is attributable on the one hand to the cosmetic preparation having to be heated for flash evaporation, and on the other hand to the characteristics of the spray mist produced by the flash evaporation, for example the droplet size and droplet density produced in the spray mist.